Python 3.3.4: python-daemon-3K ; How to use runner

Question

Struggling to try and get a python daemon to work using Python 3.3.4. Im using the latest version of the python-daemon-3K from PyPi i.e. 1.5.8

Starting point is the following code found How do you create a daemon in Python? code i believe is 2.x Python.

import time
from daemon import runner

class App():
    def __init__(self):
        self.stdin_path = '/dev/null'
        self.stdout_path = '/dev/tty'
        self.stderr_path = '/dev/tty'
        self.pidfile_path =  '/tmp/foo.pid'
        self.pidfile_timeout = 5
    def run(self):
        while True:
            print("Howdy!  Gig'em!  Whoop!")
            time.sleep(10)

app = App()
daemon_runner = runner.DaemonRunner(app)
daemon_runner.do_action()

Attempting to run this i get the following error.

python mydaemon.py start
Traceback (most recent call last): File "mydaemon.py", line 60, in daemon_runner = runner.DaemonRunner(app) File "/depot/Python-3.3.4/lib/python3.3/site-packages/python_daemon_3K-1.5.8-py3.3.egg/daemon/runner.py", line 89, in init app.stderr_path, 'w+', buffering=0) ValueError: can't have unbuffered text I/O

Any pointer how to translate to work with Python 3.3.4 or a good example of using the runner in python-daemon-3K

Thanks derek

Answer 1

To make the code run in python3 you need to make a change in the DaemonRunner class, you cannot have unbuffered text IO but you can have unbuffered bytes IO so changing the mode to'wb+' will work:

class DaemonRunner(object):

        self.parse_args()
        self.app = app
        self.daemon_context = DaemonContext()
        self.daemon_context.stdin = open(app.stdin_path, 'r') 
        # for linux /dev/tty must be opened without buffering and with b
        self.daemon_context.stdout = open(app.stdout_path, 'wb+',buffering=0)
        # w+ -> wb+
        self.daemon_context.stderr = open(
            app.stderr_path, 'wb+', buffering=0)

Answer 2

To make the code run in python3 you need to make a change in the DaemonRunner class

class DaemonRunner(object):
    self.parse_args()
    self.app = app
    self.daemon_context = DaemonContext()
    self.daemon_context.stdin = open(app.stdin_path, 'r') 
    self.daemon_context.stdout = open(app.stdout_path, 'w+')
    self.daemon_context.stderr = open(app.stderr_path, 'w+')